1. Field of the Invention
One embodiment of the present invention relates to an electrode for an energy storage device and a method for manufacturing the electrode for an energy storage device. Further, one embodiment of the present invention relates to an energy storage device having the electrode for an energy storage device.
Note that the energy storage device indicates all elements and devices which have a function of storing energy.
2. Description of the Related Art
In recent years, the development of energy storage devices such as a lithium-ion secondary battery and a lithium-ion capacitor has been conducted.
In the above electrode for an energy storage device, an active material is formed over a surface of a current collector. As the active material, a material to/from which ions functioning as carriers can be adsorbed or desorbed, such as carbon or silicon is used. For example, silicon has higher theoretical capacity than carbon and is advantageous in increasing the capacity of the energy storage device. However, the volume of silicon expands when silicon is combined with lithium during charging. On the other hand, the volume of silicon decreases when lithium is desorbed during discharging. The volume expansion and volume contraction of the active material cause mechanical damage of the negative electrode and charge-discharge cycle characteristics of the energy storage device is deteriorated. Thus, some techniques for mitigating the effect caused by the volume expansion of the active material have been proposed (for example, Patent Document 1).